/*
* << Haru Free PDF Library >> -- hpdf_encryor.c
*
* URL: http://libharu.org
*
* Copyright (c) 1999-2006 Takeshi Kanno <takeshi_kanno@est.hi-ho.ne.jp>
* Copyright (c) 2007-2009 Antony Dovgal <tony@daylessday.org>
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation.
* It is provided "as is" without express or implied warranty.
*
*------------------------------------------------------------------------------
*
* The code implements MD5 message-digest algorithm is based on the code
* written by Colin Plumb.
* The copyright of it is as follows.
*
* This code implements the MD5 message-digest algorithm.
* The algorithm is due to Ron Rivest. This code was
* written by Colin Plumb in 1993, no copyright is claimed.
* This code is in the public domain; do with it what you wish.
*
* Equivalent code is available from RSA Data Security, Inc.
* This code has been tested against that, and is equivalent,
* except that you don't need to include two pages of legalese
* with every copy.
*
* To compute the message digest of a chunk of bytes, declare an
* MD5Context structure, pass it to MD5Init, call MD5Update as
* needed on buffers full of bytes, and then call MD5Final, which
* will fill a supplied 16-byte array with the digest.
*
*---------------------------------------------------------------------------*/
#include "hpdf_conf.h"
#include "hpdf_consts.h"
#include "hpdf_utils.h"
#include "hpdf_encrypt.h"
static const HPDF_BYTE HPDF_PADDING_STRING[] = {
0x28, 0xBF, 0x4E, 0x5E, 0x4E, 0x75, 0x8A, 0x41,
0x64, 0x00, 0x4E, 0x56, 0xFF, 0xFA, 0x01, 0x08,
0x2E, 0x2E, 0x00, 0xB6, 0xD0, 0x68, 0x3E, 0x80,
0x2F, 0x0C, 0xA9, 0xFE, 0x64, 0x53, 0x69, 0x7A
};
/*---------------------------------------------------------------------------*/
/*------ MD5 message-digest algorithm ---------------------------------------*/
static void
MD5Transform (HPDF_UINT32 buf[4],
const HPDF_UINT32 in[16]);
static void
MD5ByteReverse (HPDF_BYTE *buf,
HPDF_UINT32 longs);
void
HPDF_MD5Init (struct HPDF_MD5Context *ctx)
{
ctx->buf[0] = 0x67452301;
ctx->buf[1] = 0xefcdab89;
ctx->buf[2] = 0x98badcfe;
ctx->buf[3] = 0x10325476;
ctx->bits[0] = 0;
ctx->bits[1] = 0;
}
void
HPDF_MD5Update (struct HPDF_MD5Context *ctx,
const HPDF_BYTE *buf,
HPDF_UINT32 len)
{
HPDF_UINT32 t;
/* Update bitcount */
t = ctx->bits[0];
if ((ctx->bits[0] = t + ((HPDF_UINT32) len << 3)) < t)
ctx->bits[1]++; /* Carry from low to high */
ctx->bits[1] += len >> 29;
t = (t >> 3) & 0x3f; /* Bytes already in shsInfo->data */
/* Handle any leading odd-sized chunks */
if (t) {
HPDF_BYTE *p = (HPDF_BYTE *) ctx->in + t;
t = 64 - t;
if (len < t)
{
HPDF_MemCpy (p, buf, len);
return;
}
HPDF_MemCpy (p, buf, t);
MD5ByteReverse (ctx->in, 16);
MD5Transform (ctx->buf, (HPDF_UINT32 *) ctx->in);
buf += t;
len -= t;
}
/* Process data in 64-byte chunks */
while (len >= 64) {
HPDF_MemCpy (ctx->in, buf, 64);
MD5ByteReverse (ctx->in, 16);
MD5Transform (ctx->buf, (HPDF_UINT32 *) ctx->in);
buf += 64;
len -= 64;
}
/* Handle any remaining bytes of data. */
HPDF_MemCpy (ctx->in, buf, len);
}
/*
* Final wrapup - pad to 64-byte boundary with the bit pattern
* 1 0* (64-bit count of bits processed, MSB-first)
*/
void
HPDF_MD5Final (HPDF_BYTE digest[16],
struct HPDF_MD5Context *ctx)
{
HPDF_UINT32 count;
HPDF_BYTE *p;
/* Compute number of bytes mod 64 */
count = (ctx->bits[0] >> 3) & 0x3F;
/* Set the first char of padding to 0x80. This is safe since there is
always at least one byte free */
p = ctx->in + count;
*p++ = 0x80;
/* Bytes of padding needed to make 64 bytes */
count = 64 - 1 - count;
/* Pad out to 56 mod 64 */
if (count < 8) {
/* Two lots of padding: Pad the first block to 64 bytes */
HPDF_MemSet (p, 0, count);
MD5ByteReverse (ctx->in, 16);
MD5Transform (ctx->buf, (HPDF_UINT32 *) ctx->in);
/* Now fill the next block with 56 bytes */
HPDF_MemSet (ctx->in, 0, 56);
} else {
/* Pad block to 56 bytes */
HPDF_MemSet (p, 0, count - 8);
}
MD5ByteReverse (ctx->in, 14);
/* Append length in bits and transform */
((HPDF_UINT32 *) ctx->in)[14] = ctx->bits[0];
((HPDF_UINT32 *) ctx->in)[15] = ctx->bits[1];
MD5Transform (ctx->buf, (HPDF_UINT32 *) ctx->in);
MD5ByteReverse ((HPDF_BYTE *) ctx->buf, 4);
HPDF_MemCpy ((HPDF_BYTE *)digest, (HPDF_BYTE *)ctx->buf, 16);
HPDF_MemSet ((HPDF_BYTE *)ctx, 0, sizeof (ctx)); /* In case it's sensitive */
}
/* The four core functions - F1 is optimized somewhat */
/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))
/* This is the central step in the HPDF_MD5 algorithm. */
#define HPDF_MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
/*
* The core of the MD5 algorithm, this alters an existing MD5 hash to
* reflect the addition of 16 longwords of new data. MD5Update blocks
* the data and converts bytes into longwords for this routine.
*/
static void
MD5Transform (HPDF_UINT32 buf[4],
const HPDF_UINT32 in[16])
{
register HPDF_UINT32 a, b, c, d;
a = buf[0];
b = buf[1];
c = buf[2];
d = buf[3];
HPDF_MD5STEP (F1, a, b, c, d, in[0] + 0xd76aa478, 7);
HPDF_MD5STEP (F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
HPDF_MD5STEP (F1, c, d, a, b, in[2] + 0x242070db, 17);
HPDF_MD5STEP (F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
HPDF_MD5STEP (F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
HPDF_MD5STEP (F1, d, a, b, c, in[5] + 0x4787c62a, 12);
HPDF_MD5STEP (F1, c, d, a, b, in[6] + 0xa8304613, 17);
HPDF_MD5STEP (F1, b, c, d, a, in[7] + 0xfd469501, 22);
HPDF_MD5STEP (F1, a, b, c, d, in[8] + 0x698098d8, 7);
HPDF_MD5STEP (F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
HPDF_MD5STEP (F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
HPDF_MD5STEP (F1, b, c, d, a, in[11] + 0x895cd7be, 22);
HPDF_MD5STEP (F1, a, b, c, d, in[12] + 0x6b901122, 7);
HPDF_MD5STEP (F1, d, a, b, c, in[13] + 0xfd987193, 12);
HPDF_MD5STEP (F1, c, d, a, b, in[14] + 0xa679438e, 17);
HPDF_MD5STEP (F1, b, c, d, a, in[15] + 0x49b40821, 22);
HPDF_MD5STEP (F2, a, b, c, d, in[1] + 0xf61e2562, 5);
HPDF_MD5STEP (F2, d, a, b, c, in[6] + 0xc040b340, 9);
HPDF_MD5STEP (F2, c, d, a, b, in[11] + 0x265e5a51, 14);
HPDF_MD5STEP (F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
HPDF_MD5STEP (F2, a, b, c, d, in[5] + 0xd62f105d, 5);
HPDF_MD5STEP (F2, d, a, b, c, in[10] + 0x02441453, 9);
HPDF_MD5STEP (F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
HPDF_MD5STEP (F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
HPDF_MD5STEP (F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
HPDF_MD5STEP (F2, d, a, b, c, in[14] + 0xc33707d6, 9);
HPDF_MD5STEP (F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
HPDF_MD5STEP (F2, b, c, d, a, in[8] + 0x455a14ed, 20);
HPDF_MD5STEP (F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
HPDF_MD5STEP (F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
HPDF_MD5STEP (F2, c, d, a, b, in[7] + 0x676f02d9, 14);
HPDF_MD5STEP (F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
HPDF_MD5STEP (F3, a, b, c, d, in[5] + 0xfffa3942, 4);
HPDF_MD5STEP (F3, d, a, b, c, in[8] + 0x8771f681, 11);
HPDF_MD5STEP (F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
HPDF_MD5STEP (F3, b, c, d, a, in[14] + 0xfde5380c, 23);
HPDF_MD5STEP (F3, a, b, c, d, in[1] + 0xa4beea44, 4);
HPDF_MD5STEP (F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
HPDF_MD5STEP (F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
HPDF_MD5STEP (F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
HPDF_MD5STEP (F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
HPDF_MD5STEP (F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
HPDF_MD5STEP (F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
HPDF_MD5STEP (F3, b, c, d, a, in[6] + 0x04881d05, 23);
HPDF_MD5STEP (F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
HPDF_MD5STEP (F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
HPDF_MD5STEP (F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
HPDF_MD5STEP (F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
HPDF_MD5STEP (F4, a, b, c, d, in[0] + 0xf4292244, 6);
HPDF_MD5STEP (F4, d, a, b, c, in[7] + 0x432aff97, 10);
HPDF_MD5STEP (F4, c, d, a, b, in[14] + 0xab9423a7, 15);
HPDF_MD5STEP (F4, b, c, d, a, in[5] + 0xfc93a039, 21);
HPDF_MD5STEP (F4, a, b, c, d, in[12] + 0x655b59c3, 6);
HPDF_MD5STEP (F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
HPDF_MD5STEP (F4, c, d, a, b, in[10] + 0xffeff47d, 15);
HPDF_MD5STEP (F4, b, c, d, a, in[1] + 0x85845dd1, 21);
HPDF_MD5STEP (F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
HPDF_MD5STEP (F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
HPDF_MD5STEP (F4, c, d, a, b, in[6] + 0xa3014314, 15);
HPDF_MD5STEP (F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
HPDF_MD5STEP (F4, a, b, c, d, in[4] + 0xf7537e82, 6);
HPDF_MD5STEP (F4, d, a, b, c, in[11] + 0xbd3af235, 10);
HPDF_MD5STEP (F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
HPDF_MD5STEP (F4, b, c, d, a, in[9] + 0xeb86d391, 21);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
static void
MD5ByteReverse (HPDF_BYTE *buf,
HPDF_UINT32 longs)
{
HPDF_UINT32 t;
do
{
t = (HPDF_UINT32) ((HPDF_UINT32) buf[3] << 8 | buf[2]) << 16 |
((HPDF_UINT32) buf[1] << 8 | buf[0]);
*(HPDF_UINT32 *) buf = t;
buf += 4;
}
while (--longs);
}
/*----- encrypt-obj ---------------------------------------------------------*/
static void
ARC4Init (HPDF_ARC4_Ctx_Rec *ctx,
const HPDF_BYTE *key,
HPDF_UINT key_len);
static void
ARC4CryptBuf (HPDF_ARC4_Ctx_Rec *ctx,
const HPDF_BYTE *in,
HPDF_BYTE *out,
HPDF_UINT len);
/*---------------------------------------------------------------------------*/
void
HPDF_PadOrTrancatePasswd (const char *pwd,
HPDF_BYTE *new_pwd)
{
HPDF_UINT len = HPDF_StrLen (pwd, HPDF_PASSWD_LEN + 1);
HPDF_PTRACE((" HPDF_PadOrTrancatePasswd\n"));
HPDF_MemSet (new_pwd, 0x00, HPDF_PASSWD_LEN);
if (len >= HPDF_PASSWD_LEN) {
HPDF_MemCpy (new_pwd, (HPDF_BYTE *)pwd, HPDF_PASSWD_LEN);
} else {
if (len > 0) {
HPDF_MemCpy (new_pwd, (HPDF_BYTE *)pwd, len);
}
HPDF_MemCpy (new_pwd + len, HPDF_PADDING_STRING, HPDF_PASSWD_LEN - len);
}
}
void
HPDF_Encrypt_Init (HPDF_Encrypt attr)
{
HPDF_MemSet (attr, 0, sizeof(HPDF_Encrypt_Rec));
attr->mode = HPDF_ENCRYPT_R2;
attr->key_len = 5;
HPDF_MemCpy (attr->owner_passwd, HPDF_PADDING_STRING, HPDF_PASSWD_LEN);
HPDF_MemCpy (attr->user_passwd, HPDF_PADDING_STRING, HPDF_PASSWD_LEN);
attr->permission = HPDF_ENABLE_PRINT | HPDF_ENABLE_EDIT_ALL |
HPDF_ENABLE_COPY | HPDF_ENABLE_EDIT | HPDF_PERMISSION_PAD;
}
void
HPDF_Encrypt_CreateOwnerKey (HPDF_Encrypt attr)
{
HPDF_ARC4_Ctx_Rec rc4_ctx;
HPDF_MD5_CTX md5_ctx;
HPDF_BYTE digest[HPDF_MD5_KEY_LEN];
HPDF_BYTE tmppwd[HPDF_PASSWD_LEN];
HPDF_PTRACE((" HPDF_Encrypt_CreateOwnerKey\n"));
/* create md5-digest using the value of owner_passwd */
/* Algorithm 3.3 step 2 */
HPDF_MD5Init(&md5_ctx);
HPDF_MD5Update(&md5_ctx, attr->owner_passwd, HPDF_PASSWD_LEN);
HPDF_PTRACE(("@ Algorithm 3.3 step 2\n"));
HPDF_MD5Final(digest, &md5_ctx);
/* Algorithm 3.3 step 3 (Revision 3 only) */
if (attr->mode == HPDF_ENCRYPT_R3) {
HPDF_UINT i;
for (i = 0; i < 50; i++) {
HPDF_MD5Init(&md5_ctx);
/* HPDF_MD5Update (&md5_ctx, digest, HPDF_MD5_KEY_LEN); */
HPDF_MD5Update (&md5_ctx, digest, attr->key_len);
HPDF_MD5Final(digest, &md5_ctx);
HPDF_PTRACE(("@ Algorithm 3.3 step 3 loop %u\n", i));
}
}
/* Algorithm 3.3 step 4 */
HPDF_PTRACE(("@ Algorithm 3.3 step 7 loop 0\n"));
ARC4Init (&rc4_ctx, digest, attr->key_len);
HPDF_PTRACE(("@ Algorithm 3.3 step 5\n"));
/* Algorithm 3.3 step 6 */
HPDF_PTRACE(("@ Algorithm 3.3 step 6\n"));
ARC4CryptBuf (&rc4_ctx, attr->user_passwd, tmppwd, HPDF_PASSWD_LEN);
/* Algorithm 3.3 step 7 */
HPDF_PTRACE(("@ Algorithm 3.3 step 7\n"));
if (attr->mode == HPDF_ENCRYPT_R3) {
HPDF_BYTE tmppwd2[HPDF_PASSWD_LEN];
HPDF_UINT i;
for (i = 1; i <= 19; i++) {
HPDF_UINT j;
HPDF_BYTE new_key[HPDF_MD5_KEY_LEN];
for (j = 0; j < attr->key_len; j++)
new_key[j] = (HPDF_BYTE)(digest[j] ^ i);
HPDF_PTRACE(("@ Algorithm 3.3 step 7 loop %u\n", i));
HPDF_MemCpy (tmppwd2, tmppwd, HPDF_PASSWD_LEN);
ARC4Init(&rc4_ctx, new_key, attr->key_len);
ARC4CryptBuf(&rc4_ctx, tmppwd2, tmppwd, HPDF_PASSWD_LEN);
}
}
/* Algorithm 3.3 step 8 */
HPDF_PTRACE(("@ Algorithm 3.3 step 8\n"));
HPDF_MemCpy (attr->owner_key, tmppwd, HPDF_PASSWD_LEN);
}
void
HPDF_Encrypt_CreateEncryptionKey (HPDF_Encrypt attr)
{
HPDF_MD5_CTX md5_ctx;
HPDF_BYTE tmp_flg[4];
HPDF_PTRACE((" HPDF_Encrypt_CreateEncryptionKey\n"));
/* Algorithm3.2 step2 */
HPDF_MD5Init(&md5_ctx);
HPDF_MD5Update(&md5_ctx, attr->user_passwd, HPDF_PASSWD_LEN);
/* Algorithm3.2 step3 */
HPDF_MD5Update(&md5_ctx, attr->owner_key, HPDF_PASSWD_LEN);
/* Algorithm3.2 step4 */
HPDF_PTRACE(("@@@ permission =%d\n", attr->permission));
tmp_flg[0] = (HPDF_BYTE)(attr->permission);
tmp_flg[1] = (HPDF_BYTE)(attr->permission >> 8);
tmp_flg[2] = (HPDF_BYTE)(attr->permission >> 16);
tmp_flg[3] = (HPDF_BYTE)(attr->permission >> 24);
HPDF_MD5Update(&md5_ctx, tmp_flg, 4);
/* Algorithm3.2 step5 */
HPDF_PTRACE(("@ Algorithm 3.2 step 5\n"));
HPDF_MD5Update(&md5_ctx, attr->encrypt_id, HPDF_ID_LEN);
HPDF_MD5Final(attr->encryption_key, &md5_ctx);
/* Algorithm 3.2 step6 (Revision 3 only) */
if (attr->mode == HPDF_ENCRYPT_R3) {
HPDF_UINT i;
for (i = 0; i < 50; i++) {
HPDF_PTRACE(("@ Algorithm 3.3 step 6 loop %u\n", i));
HPDF_MD5Init(&md5_ctx);
HPDF_MD5Update (&md5_ctx, attr->encryption_key, attr->key_len);
HPDF_MD5Final(attr->encryption_key, &md5_ctx);
}
}
}
void
HPDF_Encrypt_CreateUserKey (HPDF_Encrypt attr)
{
HPDF_ARC4_Ctx_Rec ctx;
HPDF_PTRACE((" HPDF_Encrypt_CreateUserKey\n"));
/* Algorithm 3.4/5 step1 */
/* Algorithm 3.4 step2 */
ARC4Init(&ctx, attr->encryption_key, attr->key_len);
ARC4CryptBuf(&ctx, HPDF_PADDING_STRING, attr->user_key, HPDF_PASSWD_LEN);
if (attr->mode == HPDF_ENCRYPT_R3) {
HPDF_MD5_CTX md5_ctx;
HPDF_BYTE digest[HPDF_MD5_KEY_LEN];
HPDF_BYTE digest2[HPDF_MD5_KEY_LEN];
HPDF_UINT i;
/* Algorithm 3.5 step2 (same as Algorithm3.2 step2) */
HPDF_MD5Init(&md5_ctx);
HPDF_MD5Update(&md5_ctx, HPDF_PADDING_STRING, HPDF_PASSWD_LEN);
/* Algorithm 3.5 step3 */
HPDF_MD5Update(&md5_ctx, attr->encrypt_id, HPDF_ID_LEN);
HPDF_MD5Final(digest, &md5_ctx);
HPDF_PTRACE(("@ Algorithm 3.5 step 3\n"));
/* Algorithm 3.5 step4 */
ARC4Init(&ctx, attr->encryption_key, attr->key_len);
ARC4CryptBuf(&ctx, digest, digest2, HPDF_MD5_KEY_LEN);
HPDF_PTRACE(("@ Algorithm 3.5 step 4\n"));
/* Algorithm 3.5 step5 */
for (i = 1; i <= 19; i++) {
HPDF_UINT j;
HPDF_BYTE new_key[HPDF_MD5_KEY_LEN];
HPDF_PTRACE(("@ Algorithm 3.5 step 5 loop %u\n", i));
for (j = 0; j < attr->key_len; j++)
new_key[j] = (HPDF_BYTE)(attr->encryption_key[j] ^ i);
HPDF_MemCpy (digest, digest2, HPDF_MD5_KEY_LEN);
ARC4Init(&ctx, new_key, attr->key_len);
ARC4CryptBuf(&ctx, digest, digest2, HPDF_MD5_KEY_LEN);
}
/* use the result of Algorithm 3.4 as 'arbitrary padding' */
HPDF_MemSet (attr->user_key, 0, HPDF_PASSWD_LEN);
HPDF_MemCpy (attr->user_key, digest2, HPDF_MD5_KEY_LEN);
}
}
void
ARC4Init (HPDF_ARC4_Ctx_Rec *ctx,
const HPDF_BYTE *key,
HPDF_UINT key_len)
{
HPDF_BYTE tmp_array[HPDF_ARC4_BUF_SIZE];
HPDF_UINT i;
HPDF_UINT j = 0;
HPDF_PTRACE((" ARC4Init\n"));
for (i = 0; i < HPDF_ARC4_BUF_SIZE; i++)
ctx->state[i] = (HPDF_BYTE)i;
for (i = 0; i < HPDF_ARC4_BUF_SIZE; i++)
tmp_array[i] = key[i % key_len];
for (i = 0; i < HPDF_ARC4_BUF_SIZE; i++) {
HPDF_BYTE tmp;
j = (j + ctx->state[i] + tmp_array[i]) % HPDF_ARC4_BUF_SIZE;
tmp = ctx->state[i];
ctx->state[i] = ctx->state[j];
ctx->state[j] = tmp;
}
ctx->idx1 = 0;
ctx->idx2 = 0;
}
void
ARC4CryptBuf (HPDF_ARC4_Ctx_Rec *ctx,
const HPDF_BYTE *in,
HPDF_BYTE *out,
HPDF_UINT len)
{
HPDF_UINT i;
HPDF_UINT t;
HPDF_BYTE K;
HPDF_PTRACE((" ARC4CryptBuf\n"));
for (i = 0; i < len; i++) {
HPDF_BYTE tmp;
ctx->idx1 = (HPDF_BYTE)((ctx->idx1 + 1) % 256);
ctx->idx2 = (HPDF_BYTE)((ctx->idx2 + ctx->state[ctx->idx1]) % 256);
tmp = ctx->state[ctx->idx1];
ctx->state[ctx->idx1] = ctx->state[ctx->idx2];
ctx->state[ctx->idx2] = tmp;
t = (ctx->state[ctx->idx1] + ctx->state[ctx->idx2]) % 256;
K = ctx->state[t];
out[i] = (HPDF_BYTE)(in[i] ^ K);
}
}
void
HPDF_Encrypt_InitKey (HPDF_Encrypt attr,
HPDF_UINT32 object_id,
HPDF_UINT16 gen_no)
{
HPDF_MD5_CTX ctx;
HPDF_UINT key_len;
HPDF_PTRACE((" HPDF_Encrypt_Init\n"));
attr->encryption_key[attr->key_len] = (HPDF_BYTE)object_id;
attr->encryption_key[attr->key_len + 1] = (HPDF_BYTE)(object_id >> 8);
attr->encryption_key[attr->key_len + 2] = (HPDF_BYTE)(object_id >> 16);
attr->encryption_key[attr->key_len + 3] = (HPDF_BYTE)gen_no;
attr->encryption_key[attr->key_len + 4] = (HPDF_BYTE)(gen_no >> 8);
HPDF_PTRACE(("@@@ OID=%u, gen_no=%u\n", (HPDF_INT)object_id, gen_no));
HPDF_MD5Init(&ctx);
HPDF_MD5Update(&ctx, attr->encryption_key, attr->key_len + 5);
HPDF_MD5Final(attr->md5_encryption_key, &ctx);
key_len = (attr->key_len + 5 > HPDF_ENCRYPT_KEY_MAX) ?
HPDF_ENCRYPT_KEY_MAX : attr->key_len + 5;
ARC4Init(&attr->arc4ctx, attr->md5_encryption_key, key_len);
}
void
HPDF_Encrypt_Reset (HPDF_Encrypt attr)
{
HPDF_UINT key_len = (attr->key_len + 5 > HPDF_ENCRYPT_KEY_MAX) ?
HPDF_ENCRYPT_KEY_MAX : attr->key_len + 5;
HPDF_PTRACE((" HPDF_Encrypt_Reset\n"));
ARC4Init(&attr->arc4ctx, attr->md5_encryption_key, key_len);
}
void
HPDF_Encrypt_CryptBuf (HPDF_Encrypt attr,
const HPDF_BYTE *src,
HPDF_BYTE *dst,
HPDF_UINT len)
{
ARC4CryptBuf(&attr->arc4ctx, src, dst, len);
}
/*--------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------*/
